SYNTHESIS AND ION SELECTIVITY OF MACROCYCLIC METACYCLOPHANES ANALOGOUS TO SPHERAND-TYPE CALIXARENES

Novel macrocyclic compounds, hexahydroxy[1.0.1.0.1.0]- (2b) and octahy droxy[1.0.1.0-1.0.1.0]metacyclophane (2c) have been prepared in 50-70% yield by base-catalyzed condensation of 5,5'-di-tert-butyl-2,2'-dihyd roxybipheny (1) with formaldehyde in refluxing xylene. An attempted al kylation of the flexible macrocycles 2b and 2c with ethyl bromoacetate in the presence of Cs2CO3 under acetonitrile reflux gave only one pur e stereoisomer 3 and 4, respectively, while other possible isomers wer e not observed. The structural characterization of these products is a lso discussed. The two-phase solvent extraction data indicated that he xaethyl ester 3 and octaethyl ester 4 show strong metal affinity, comp arable with that of the corresponding calix[n]arenes, and a high K+ se lectivity was observed for octaethyl ester 4. H-1-NMR titration of hex aethyl ester 3 and octaethyl ester 4 with KSCN clearly demonstrate tha t a 1 : 1 complex is formed which is stable on the NMR time scale.